As recently as 153 BC, March was the first month of the year. It’s named for Mars, the Roman god of war, but he was also known as the guardian of agriculture. For us in the northern hemisphere, March marks the beginning of spring.

This year spring starts at 5:58 p.m. on Wednesday the 20th. It’s an extraordinary moment for everyone on Earth because March 20 and the fall equinox are the only two days each year that the sun rises exactly due east and sets exactly due west. The days also will be precisely 12 hours long within a few days of the spring and fall equinoxes for everyone on Earth, except those at the North and South poles.

The first day of spring is further defined by the sun on the ecliptic crossing over the celestial equator in an upward motion. Then the days continue to get longer until the summer solstice on June 21, when they will start to get shorter again each day for the next six months until the winter solstice rolls around again.

Although this winter hasn’t been particularly harsh, it’s always nice to welcome spring back to Maine. We’ll have warmer and shorter nights to enjoy the late winter and early spring skies. The good meteor showers won’t start until next month and no new comets have been discovered, breaking our string of five or six good comets in recent months. But you can look forward to three bright planets in the morning sky playing celestial tag with the moon, and you’ll get a great chance to spot the elusive zodiacal light for several weeks without even having to get up early.

Quite a celestial dance will go on in the morning sky all month. Now that Saturn has caught up with and passed Venus, notice that both Saturn and Jupiter will continue to climb higher into our morning sky and rise a little earlier each morning. Venus, meanwhile, will sink a little lower and set a little earlier each morning. Toward the end of March, Mercury will make a short appearance very low in the morning sky.

Jupiter is the first planet to rise in the morning sky, by 2 a.m. at the start of the month and 1 a.m. by the end of March. It will cross the midnight threshold next month on its way to opposition by early June just before summer. Notice that it’s also getting larger and brighter each morning as we continue to catch up with it in the sky. Remember that we have the highly successful Juno mission circling the planet every 53 days in a highly elliptical orbit to avoid Jupiter’s powerful radiation fields. Juno is about halfway through its mission, which should end sometime in 2021. Many great and unexpected pictures of Jupiter have been taken over the last couple of years, including some new ones of volcanoes on Io. A pair of binoculars will allow you to see the four largest Galilean moons of Jupiter’s 79 moons.

Saturn rises about two hours after Jupiter. Notice that Jupiter shines about 10 times brighter than Saturn and is located just to the right – or west – of Sagittarius, and Saturn is just to the left – or west – of the teapot asterism in Sagittarius the Archer. Jupiter is ever so slowly catching up with Saturn. The two will finally appear to meet low in the evening sky in December 2020. It’s a fairly rare event because Jupiter takes 12 years to orbit the sun while Saturn takes 29 years, so they are seldom seen in the same constellation in our sky.

The moon will pass very close to Saturn twice this month. The slender waning crescent moon will be just above and to the right of Saturn on the first morning of March. Then it will pass just above and to the right of Venus the next morning. The last-quarter moon will again pass very close to Saturn on the mornings of the 28th and 29th.

Venus, the last morning planet to rise, is also the brightest by far – six times brighter than Jupiter or about 60 times brighter than Saturn. It rises about two hours before the sun to start the month, but will rise only an hour before the sun by the end of March as it slowly sinks into the morning twilight. Come late July, we will completely lose it in the morning sky. Through a telescope you can tell Venus is slowly getting more illuminated by the sun even as it gets a little dimmer and farther away from Earth. It will be 81 percent full by the end of March.

For most of the month, Mars will be the only evening planet – except when Mercury puts in a brief appearance in the first week of March. Mars continues to set around the same time each night, roughly 11 p.m. That will shift to midnight after daylight saving time starts on the 10th. Notice that Mars is getting a little fainter and smaller each night as we pull farther ahead of it in our orbits.

Mars is entering a very beautiful part of the sky in the Winter Hexagon, now in Taurus. When spring starts, it will be passing just below the Pleiades star cluster. The Pleiades, also called the Seven Sisters, is an open star cluster that contains about 500 young stars located about 400 light years away. Galileo first improved the telescope and used it for astronomy in 1609 – bear with me a moment and you’ll see where I’m going. That marked a huge leap for mankind because we could now see distant celestial objects as if they were right in front of us. His invention changed a lot of incorrect beliefs and pushed our knowledge forward on many fronts. The next time you look at this lovely star cluster, remember that the very photons entering your eyes in that instant left their source, this distinct and unique little star cluster, about the time Galileo turned the first telescope in human history up to the heavens. He hoped the instrument could help him and all humans learn about the true nature of our universe.

The zodiacal light is best seen only twice each year, about an hour after sunset in March in the western sky or about an hour before sunrise in the east in the fall (when you have to get up early to see it but it’s worth it). It’s visible because the angle of the ecliptic to the horizon is at its steepest those two times of each year.

The zodiacal light can take on many shapes but is usually seen as a faintly glowing pyramid or haystack of subtle light stretching upward along the ecliptic. It is usually much brighter and easier to see the farther south you go nearer the equator. In all my years of stargazing, I have seen it just three times. It is created by sunlight bouncing off grains of dust and ice forming a torus in the ecliptic plane.

These grains range from a micron up to a meter. They are the 4.6 billion-year-old primordial matter that is now left over from the original dynamic, chaotic formation of the inner planets in our solar system.

MARCH HIGHLIGHTS

March 1: Venus, Saturn, and Jupiter arc across the morning sky with the waning crescent moon for several mornings. The moon will actually occult Saturn in some places on Earth.

March 6: New moon is at 11:05 a.m.

March 10: Daylight saving time starts at 2 a.m.

March 11: The moon will pass close to Mars.

March 13: William Herschel discovered Uranus on this day in 1781.

March 14. Albert Einstein was born on this day in 1879. He thought of General Relativity in 1915. First-quarter moon is at 6:28 a.m.

March 16: Caroline Herschel was born on this day in 1750. She worked closely with her brother, William, and they were both accomplished musicians.

March 19: Margaret Harwood was born on this day in 1885. She was an American astronomer and the first director of the Maria Mitchell Observatory on Nantucket.

March 20: Full moon is at 9:44 p.m. This is also called the Worm, Sap, Lenten or Crow Moon. Spring starts at 5:58 p.m.

March 28: Last-quarter moon is at 12:11 a.m.

March 29: The moon passes close to Saturn again this morning.

Bernie Reim of Wells is co-director of the Astronomical Society of Northern New England

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